When setting up a Raft Aquaponics System, Please take the time to test a sample of your intended paint before you spend time painting all your rafts.
The Dow Blue Board that most people use for their rafts in DWC aquaponics is not UV stable and the foam exposed to sun will deteriorate. A simple coat of good white exterior latex paint can go a long way to keeping your foam rafts from shedding foam dust into your system. A nice gloss will stay easier to clean than a mat or low luster paint.
Now I write this post because I have discovered that not all paints are created equal. So even if you know your paint will be good, it might be a good idea to paint some sample bits of foam and let the paint dry so you can find out how long it will take to set and cure properly before you can wash them off. You do want to rinse the rafts well before putting them into the system. Paints have some soap in them and you want to rinse off all traces of that soap before you put it in your system. Some paints will dry quickly and be ready for rinsing after only a couple days while other paints may take far longer especially under cool or wet conditions.
Now I know some people who have used pricy fish safe paints to paint the rafts top bottom and sides while others just use a basic exterior latex paint on only the tops of the rafts. My rafts are painted on top and rinsed well before they are put into my system and doing fine so far (But I’ve only been doing Raft aquaponics for less than half a year now.)
Rafts are easy for planting/harvesting large numbers of single types of plants at once. And they are handy for growing living lettuce for sale.